19655904661 has 2 divisors, whose sum is σ = 19655904662. Its totient is φ = 19655904660.

The previous prime is 19655904659. The next prime is 19655904761. The reversal of 19655904661 is 16640955691.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19514413636 + 141491025 = 139694^2 + 11895^2 .

It is a cyclic number.

It is not a de Polignac number, because 19655904661 - 2¹ = 19655904659 is a prime.

Together with 19655904659, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 19655904599 and 19655904608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19655904761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9827952330 + 9827952331.

It is an arithmetic number, because the mean of its divisors is an integer number (9827952331).

Almost surely, 2^19655904661 is an apocalyptic number.

It is an amenable number.

19655904661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19655904661 is an equidigital number, since it uses as much as digits as its factorization.

19655904661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1749600, while the sum is 52.

The spelling of 19655904661 in words is "nineteen billion, six hundred fifty-five million, nine hundred four thousand, six hundred sixty-one".